Email deliverability, settings, management and IP Reputation

I need someone who has experience with a Bluehost VPS configuration, using WHM Control Panel, and fully understanding Email deliverability issues. Specifically need help with how to improve IP reputation so that mail is not blocked by services like CloudMark, Spamhaus, Spamcop, etc. Have been blacklisted in the past by Barracuda, and a couple of others. Followed their instructions, and were removed from all blacklists. Recently, although not blacklisted, emails started being blocked or filtered again.